What was the first artificial satellite launched into space?

The first artificial satellite launched into space was Sputnik 1. This satellite was launched by the Soviet Union on October 4, 1957. It marked a significant milestone in space exploration as it was the first human-made object to orbit the Earth, thereby initiating the space age and the subsequent space race between the United States and the Soviet Union. Sputnik 1 transmitted radio pulses back to Earth, providing valuable data about the ionosphere and demonstrating the feasibility of sending objects into orbit.

Looking at the other options, Explorer 1, launched in 1958, was the United States' first satellite but came after Sputnik 1. Skylab was America's first space station, launched in 1973, while Apollo 11 was the mission that successfully landed humans on the Moon in 1969. Neither Explorer 1, Skylab, nor Apollo 11 holds the distinction of being the first artificial satellite, underscoring Sputnik 1's groundbreaking role in the history of space exploration.